Pictures of the day: 13 January 2012

This cheeky chimp couldn't resist taking a quick peek down his keeper's top as she held him close to her chest. Photographer Cyril Ruoso captured the moment at Pandrillus Drill Sanctuary, Nigeria. He said: "It's a funny shot. However, for the chimp his actions have a social meaning. Grooming or physical interaction is a way to show how close you are to another individual. This isn't the first time I have seen apes taking an interest in humans. I once met an Orangutan in Borneo who loved to groom my hairy chest even when I was wearing a shirt."